The invention is concerned with a flexible element having a core and a tubular sheathing protecting the latter, and sleeve elements which surround the core and between which the tubular sheathing is held, the core and the tubular sheathing having different coefficients of thermal expansion.
In the case of flexible elements, for example pliant flexible shafts or Bowden cables, in which the forces or moments can be transmitted by the core, or else in the case of electric lines, there is a fundamental problem of the protecting sheathings, which generally consist of plastic, having a considerably different coefficient of thermal expansion in comparison with the core which consists, for example, of steel or another metal on account of the mechanical stress or in order to achieve electric conductivity. The sleeves have previously been bonded or welded to the tube, with the result that when the sleeves are fixed axially and the core is fixed axially, problems may occur because of the different expansions due to temperature. This results in distortions of the flexible element, which may, for example in the case of drive elements, ensure that the element moves from its originally designated position, but at least cause frictional losses and an increased wear due to the bearing forces between the tubular sheathing and core. If the different expansions due to temperature are compensated for by cores which are fixed in an axially movable manner, there has to be the risk of the expanding tube pulling the core out of its guide, which should be avoided under all circumstances.